JP4275512B2 - Dielectric resonator, dielectric filter, and wireless communication device - Google Patents

Description

  The present invention relates to a dielectric resonator and a dielectric filter used in the millimeter wave band, and a wireless communication device using the dielectric filter.

In recent years, communication systems such as a wireless LAN have been studied in the millimeter wave band, and research on passive elements used therefor has been actively conducted.
Currently, the challenge of passive devices in the millimeter wave band is to reduce the size and cost. The problem for cost reduction is processing accuracy that can be mass-produced for small dimensions. Usually, if the technology that is mass-produced in the microwave band is applied to millimeter waves, the parts become too small, and therefore the dimensional variation becomes large with the machining accuracy capable of mass production. For this reason, the unit price of the parts was high.

  Conventionally, as a resonator used in the microwave and millimeter wave bands, there is a TE010 mode dielectric loaded cavity resonator (see Patent Document 1). As shown in FIG. 6, this resonator has a structure in which a dielectric substrate 1 is arranged at the center of a cavity resonator surrounded by metal conductors 2b, 3a, 3b. This structure is very convenient in the microwave band because the electric field concentrates on the dielectric, and has been actively used for miniaturization of the resonator.

The dielectric resonator is also used for a dielectric filter for millimeter wave band. A dielectric filter is formed by coupling a plurality of these resonators. An example of this structure is shown in FIG. In FIG. 7, the cavity resonators are vertically arranged in two stages, and the dielectric substrates 1a and 1b are arranged in the portions where the electric field is strong.
JP-A-8-265015

However, when designing the dielectric-loaded cavity resonator and the dielectric filter using the dielectric resonator, the size becomes too small if it is used in the millimeter wave band, and the limit of manufacturing accuracy becomes a problem.
Therefore, if the dielectric is made thin in order to suppress the concentration of the electric field on the dielectric, the dimensional accuracy becomes a problem, and the strength of the dielectric becomes weak.

Therefore, according to the present invention, the resonant frequency can be increased by arranging the dielectric in a weak place instead of placing it in a place where the electric field is strong as in the above structure. As a result, the design accuracy of the resonant frequency can be increased. It is an object of the present invention to provide a dielectric resonator and a dielectric filter capable of improving the frequency, and a wireless communication device using the dielectric filter.
Another object of the present invention is to provide a dielectric resonator and a dielectric filter that can simplify the manufacturing process and reduce costs, and a wireless communication device using the dielectric filter.

(1) As a result of repeated studies on the above problems, the present inventor has arranged a dielectric plate on a conductor plate, a bottomed cylindrical conductor on the dielectric plate, and an opening portion of the dielectric plate. Was placed in contact with. A plurality of the resonators are prepared, and a dielectric filter having an input electrode for inputting a high frequency signal to the resonance portion and an output electrode for extracting the high frequency signal has been invented.
That dielectric resonator of the present invention includes a lower conductive body, a dielectric substrate disposed in contact with the lower conductor, and a bottomed tubular conductor made of a cylindrical conductor and the upper conductor, the chromatic An opening end of the bottom cylindrical conductor opposite to the upper conductor is disposed so as to contact the dielectric substrate, and a resonance cavity surrounded by the lower conductor and the bottomed cylindrical conductor is provided. It is formed.

  The dielectric resonator according to the present invention utilizes the fact that the electric field in the cavity becomes zero on the lower electrode surface. For this reason, the electric field energy accumulated in the dielectric substrate can be reduced as compared with the conventional resonator. When designed under the same conditions (dielectric constant, dielectric thickness, cavity height, opening diameter, etc.), the resonant frequency can be increased without having to make the size very small compared to conventional resonators. Designed and suitable as a millimeter-wave resonator. That is, there is an advantage that the size of the opening can be increased as compared with the conventional millimeter-wave band resonator. Therefore, it is possible to manufacture a dielectric resonator more easily than in the past.

In order to confine a radio wave in a space and resonate at a frequency to be used, the periphery of the dielectric resonator needs to have a structure shielded by a conductor.
Examples of this, the support member is tubular conductor, for example, a cylindrical conductor, together with the upper conductor forms a bottom surface of the cylindrical conductor, the open end of the tubular conductor is brought into contact with the dielectric substrate The structure is shown.

Et al is said to sandwich the dielectric substrate, for radio waves from the waveguide formed between the end face of the support member and the lower conductor does not leak, the dielectric substrate, the resonant frequency RF signal It is necessary to have a thickness and a relative dielectric constant so as to attenuate the propagation of.

(2) In addition, the inventor prepares one or more dielectric resonators, forms an input electrode for inputting a high frequency signal to the resonance part, and an output electrode for outputting the high frequency signal, and forms a dielectric Realized the filter.
That is, the dielectric filter of the present invention includes a lower conductor and an upper conductor, and a dielectric substrate disposed in contact with the lower conductor, and the dielectric substrate and the upper conductor are interposed via a support member. A resonance space is formed between the input electrode and the input electrode for inputting a high-frequency signal to the resonance space; and an output electrode for extracting the high-frequency signal from the resonance space, and at least one of the input electrode and the output electrode, or both Kopu Les over Na line, strip line, characterized in that it is formed by a coaxial line, or non-radioactive line.

A plurality of the resonance spaces are formed, and an input electrode formed by a coaxial line that inputs a high frequency signal to any one of the resonance spaces, and an output electrode formed by a coaxial line that outputs a high frequency signal from another resonance space It may be provided. According to this configuration, since the dielectric resonators are formed in parallel in the horizontal direction, it is possible to realize a dielectric filter at about half the height of the conventional one.

In the waveguide formed between the lower conductor and the end face of the support member across the dielectric substrate, the dielectric substrate propagates a high-frequency signal having a resonance frequency in order to prevent leakage of radio waves. It is preferable to have a thickness and a relative dielectric constant that attenuates.
The dielectric filter of the present invention includes a lower conductor and an upper conductor, a first dielectric substrate disposed in contact with the lower conductor, and a second dielectric substrate disposed in contact with the upper conductor. The first dielectric substrate and the second dielectric substrate are opposed to each other via a support member, a resonance space is formed therebetween, and an input electrode for inputting a high frequency signal to the resonance space If, and an output electrode for taking out the high-frequency signal from said resonant space, the input electrode or output electrode, at least one or both, Kopu Les over Na line, strip line, formed by the coaxial line, or non-radioactive lines It is characterized by.

This dielectric filter has a structure in which dielectric resonators are vertically arranged, and the lateral width of the dielectric filter can be reduced.
At a frequency to be used, in order to resonate trapped radio waves into space, surrounding dielectric resonators are required and Turkey are shielded by a conductor. Examples of this, the support member is a tubular conductor, for example, cylindrical conductor, both open ends of the tubular conductor, the two are brought into contact with the dielectric substrate structure is shown.

Further, in order to prevent radio waves from leaking from the waveguide formed between the upper conductor or the lower conductor and the end face of the support member with the dielectric substrate interposed therebetween, the dielectric substrate has a high frequency of a resonance frequency. It is necessary to have a thickness and a relative dielectric constant that attenuate signal propagation .

By mounting the pre Symbol dielectric filter in a wireless communication device, it is possible to provide a low cost, excellent millimeter wave radar small in performance, a wireless LAN, hot spot, a wireless communication device such as an ad hoc wireless systems.

  According to the present invention, a dielectric resonator is provided with a dielectric plate disposed on a conductor plate, and a bottomed cylindrical conductor placed on the dielectric plate so that the opening is on the dielectric plate side. By using this dielectric resonator, it is possible to realize a dielectric filter and a wireless communication device that can be expected to be low in cost, downsized, and high in performance, particularly in the millimeter wave band.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 is a longitudinal sectional view showing an example of a dielectric resonator according to the present invention. In FIG. 1, the dielectric resonator has a dielectric substrate 1 disposed on a lower conductor 3 serving as a ground, and a bottomed cylindrical conductor 2 having an opening 4 on the dielectric substrate 1. The opening end of the dielectric substrate 1 is in contact with the dielectric substrate 1. The bottomed cylindrical conductor 2 includes a bottom plate 2a and a cylindrical side plate (corresponding to a support member) 2b. Therefore, the lower conductor 3 and the bottomed cylindrical conductor 2 form a resonance cavity surrounded by metal.

The lower conductor 3 and the bottom plate 2a of the bottomed cylindrical conductor 2 are both shown in plan view and have a disk shape, and are arranged in parallel to each other. The diameter of the cavity constituted by the bottomed cylindrical conductor 2 is D, the height is H, and the thickness of the dielectric substrate 1 is t.
A coaxial line 5 is inserted into the cavity on the cylindrical side plate 2 b of the bottomed cylindrical conductor 2. Thus, excitation and detection of the dielectric resonator can be performed via the loop antenna 6 attached to the tip of the coaxial line 5.

Note that the out electrodes of the signal is not limited to the coaxial line, Kopu les over Na lines, strip lines may be formed by a microstrip line, or non-radioactive line.
This dielectric resonator utilizes the TE010 mode, and the electric field becomes zero on the surface of the lower conductor 3 of the dielectric resonator and then increases upward. For this reason, the electric field energy of the TE010 mode accumulated in the dielectric substrate 1 disposed in contact with the lower conductor 3 is the electric field accumulated in the dielectric substrate 1 of the conventional TE010 mode dielectric resonator shown in FIG. Smaller than energy.

  Therefore, when designed under the same conditions (dielectric thickness, relative dielectric constant, cavity height H, opening diameter D, etc.), the dielectric resonator of the present invention is compared with the conventional TE010 mode dielectric resonator. Therefore, it can be designed to have a high frequency and is suitable as a dielectric resonator in the millimeter wave band. If the frequency is the same, there is an advantage that the height H of the cavity can be increased and the size D of the opening can be increased as compared with the conventional dielectric resonator.

As a result, the demand for processing errors in manufacturing the dielectric resonator is relaxed, and the manufacture of the dielectric resonator is facilitated.
The cylindrical side plate 2b of the bottomed cylindrical conductor 2 may be formed integrally with the bottom plate 2a or may be formed separately. The cylindrical side plate 2b may be a conductor or a dielectric when formed separately. When the cylindrical side plate 2b is a dielectric, its height (Ht) is such that the propagation mode becomes a cut-off region when electromagnetic waves propagate in the horizontal direction between the upper and lower conductors 2a and 3 at the frequency used. It is preferable to select a high height. This is to prevent radio waves in the cavity from leaking between the upper and lower conductors 2a, 3.

Here, the thickness t of the dielectric substrate 1 and its relative dielectric constant ε will be described. The dielectric substrate 1 is selected to have a value that attenuates a high frequency signal having a resonance frequency. Specifically, the dielectric substrate 1 has a parallel plate structure sandwiched between the lower conductor 3 and the open end 2 c of the bottomed cylindrical conductor 2. In order to prevent radio waves from jumping out from the end of the parallel plate, it is necessary to design in a frequency region that does not exceed the cutoff frequency fc of the parallel plate. In the conventional microwave band, it was not necessary to consider much, but since the wavelength is short in the millimeter wave band, a sample having a thick dielectric substrate 1 having a large thickness t and a high relative dielectric constant ε exceeds the cutoff frequency fc. Also occurs. The cutoff frequency fc of the parallel plate is expressed by the following formula (μ is magnetic permeability).
fc = 1 / 2t√ (με)
Therefore, it is necessary to select the thickness t and the relative dielectric constant ε of the dielectric substrate 1 so that the frequency to be used does not exceed the cutoff frequency fc.

As the dielectric substrate 1, for example, an organic dielectric substrate such as glass epoxy resin or an inorganic dielectric substrate such as ceramic material is used.
In particular, if a ceramic material is used, the dielectric constant of the ceramic dielectric is usually 5 to 25, which is higher than that of the resin substrate. Therefore, the dielectric layer can be made thin, which is effective for miniaturization of the element. In addition, when a ceramic material is used, since the dielectric loss is generally lower than that of the resin substrate, it is effective for increasing the Q of the dielectric filter.

The conductor material is gold, silver, copper or the like.
FIG. 2A is a longitudinal sectional view showing an example of the basic structure of the dielectric filter of the present invention. FIG. 2B is a perspective view of the dielectric filter of the present invention.
2 (a) and 2 (b), the dielectric substrate 1 is disposed on the lower conductor 3, and the dielectric substrate 1 has a rectangular parallelepiped shape and has two openings 4a and 4b. The bottom conductor 2 is installed. The two openings 4 a and 4 b are arranged with a distance x through which the desired coupling coefficient can be obtained via the dielectric substrate 1. The signal input to the dielectric filter and the signal output from the dielectric filter can be performed from the side surface of the bottomed conductor 2 as in FIG.

When this dielectric filter is applied to the millimeter wave band, it is necessary that the two dielectric resonators have a predetermined resonance frequency. The “predetermined relationship” varies depending on the purpose of use of the dielectric filter. The resonance frequency may be the same or the resonance frequency may be shifted.
As described with reference to FIG. 1, the dielectric filter has a moderate dimensional tolerance with respect to the design value D of the opening. Therefore, if the dimensional processing accuracy is the same, the accuracy of the resonance frequency is improved as compared with the conventional case. ing. Therefore, it is possible to manufacture a dielectric filter with uniform characteristics and good yield.

  Also in this dielectric filter, the supporting member, that is, the side surface 2b of the bottomed conductor 2 may be formed integrally with the bottom plate 2a, or may be formed separately. When separately formed, the cylindrical side plate 2b may be a conductor or a dielectric, and when it is a dielectric, as described above, its height (Ht) is set between the upper and lower conductors 2a and 3 at the frequency to be used. Preferably, the height is selected so that electromagnetic waves do not leak laterally. Also, the thickness t of the dielectric substrate 1 and its relative dielectric constant ε must be selected so that radio waves do not leak from the end of the dielectric substrate 1 as described above.

  FIG. 3 is a longitudinal sectional view showing an example of still another structure of the dielectric filter of the present invention. In FIG. 3, a dielectric substrate 1a is disposed on a lower conductor plate 3a, a cylindrical conductor 2b is disposed on the dielectric substrate 1a, and an opening end thereof is in contact with the dielectric substrate 1a. The second dielectric substrate 1b is disposed on the upper conductor plate 3b, and the second dielectric substrate 1b is brought into contact with the other open end of the cylindrical conductor 2b. Thus, the first dielectric substrate 1a and the second dielectric substrate 1b are arranged to face each other. The first dielectric substrate 1a and the second dielectric substrate 1b are arranged to face each other with a distance y that provides a desired coupling coefficient.

The cylindrical conductor 2b may be a conductor or a dielectric. Since it is not a shielding effect when it is a dielectric, when the electromagnetic wave propagates in the horizontal direction between the upper and lower conductors 3a and 3b at the frequency to be used, the propagation mode becomes the cutoff region. It is necessary to choose such a height.
The dielectric filter of FIG. 3 has a structure using coupling of dielectric resonators arranged vertically, and the lateral width of the dielectric filter can be reduced as compared with the structure of FIG. Further, it is necessary to select the thickness t of the dielectric substrates 1a and 1b and the relative dielectric constant ε so that radio waves do not leak from the end of the dielectric substrate 1 as described above.

FIG. 4 is a longitudinal sectional view showing an example of still another structure of the dielectric filter of the present invention. This structure is a combination of the dielectric filters shown in FIGS.
In FIG. 4, a dielectric substrate 1a is disposed on a conductor plate 3a, and a rectangular parallelepiped conductor 7 having two oblique cylindrical cavities passing therethrough is disposed thereon. A second dielectric substrate 1b is disposed on the upper end of the conductor 7, and a conductor plate 3b is disposed thereon.

  Also in this structure, the rectangular parallelepiped conductor 7 may be a metal or a dielectric, and when it is a dielectric, it does not itself have a shielding effect, so the height y of the cavity is set between the upper and lower conductors 3a and 3b at the frequency to be used. Must be selected so that the electromagnetic waves do not leak through the lateral direction. Also, the thickness t of the dielectric substrates 1a and 1b and the relative dielectric constant ε thereof must be selected so that radio waves do not leak from the ends of the dielectric substrates 1a and 1b as described above.

In the dielectric filter of FIG. 4, a high frequency signal is coupled from the tip loop antenna 6 of the coaxial line 5 inserted on the left side of the conductor 7 to the opening 4a, and is coupled to the opening 4b via the dielectric substrate 1b. Then, it is taken out from the tip loop antenna 6 of the coaxial line 5 inserted on the right side of the conductor 7. Thereby, a dielectric filter in which dielectric resonators are connected in four stages can be realized.
As described above, the resonator and the dielectric filter of the present invention are most effective particularly in the millimeter wave band, and low cost can be expected.

  Although the embodiments of the present invention have been described above, the embodiments of the present invention are not limited to the above-described embodiments, and various modifications can be made within the scope of the present invention.

A single resonator having the structure shown in FIG. 1 was designed and measured. The cavity diameter D was 11.86 mm, the height H was 6.56 mm, the dielectric thickness t was 0.63 mm, and the relative dielectric constant ε was 9.4. The calculated value is the resonance frequency f0 = 35.53 GHz.
A resonator was actually fabricated and measured using a network analyzer. The measurement result of the dimension of the cavity is D = 11.864 mm and H = 6.565 mm, sapphire is used as the dielectric, and the measurement result of the thickness t is 0.626 mm.

The frequency response of the insertion loss of this resonator is shown in FIG. At this time, the measured value was f0 = 35.57 GHz. The main cause of the deviation from the calculated value is the dielectric constant of the dielectric. If the relative permittivity of the dielectric can be accurately known, the shift of f0 is expected to be smaller.
As a result, it was found that a dielectric filter in the millimeter wave band can be sufficiently realized using this resonator.

It is a longitudinal cross-sectional view which shows the basic structure of the dielectric resonator of this invention. (A) is a longitudinal cross-sectional view which shows the structural example of the dielectric material filter of this invention. (B) is a perspective view of a dielectric filter. It is a longitudinal cross-sectional view which shows an example of the further another structure of the dielectric material filter of this invention. It is a longitudinal cross-sectional view which shows an example of the further another structure of the dielectric material filter of this invention. It is an actual measurement graph of the frequency response of insertion loss concerning the Example of the dielectric resonator of this invention. It is sectional drawing which shows an example of the structural drawing of the conventional TE mode dielectric material loading cavity resonator. It is sectional drawing which shows an example of the structural drawing of the conventional TE mode dielectric filter.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 1a, 1b Dielectric board | substrate 2 Bottomed cylindrical conductor 2b Support member 3, 3a, 3b Conductor plate 4 Cylindrical cavity 5 Coaxial line 6 Loop antenna

Claims (11)

A lower conductor, a dielectric substrate disposed in contact with the lower conductor, and a bottomed cylindrical conductor composed of a cylindrical conductor and an upper conductor;
An opening end of the bottomed cylindrical conductor opposite to the upper conductor is disposed so as to contact the dielectric substrate, and is surrounded by the lower conductor and the bottomed cylindrical conductor. A dielectric resonator characterized in that a cavity is formed.   The dielectric resonator according to claim 1, wherein the cylindrical conductor is a cylindrical conductor.   In the waveguide formed between the lower conductor and the bottomed cylindrical conductor across the dielectric substrate, the dielectric substrate has a thickness and ratio that attenuates the propagation of a high-frequency signal at a resonance frequency. The dielectric resonator according to claim 1 or 2, wherein the dielectric resonator has a dielectric constant. A lower conductor and an upper conductor, and a dielectric substrate disposed in contact with the lower conductor;
The dielectric substrate and the upper conductor face each other via a support member, and a resonance space is formed between them,
An input electrode for inputting a high-frequency signal to the resonance space; and an output electrode for extracting a high-frequency signal from the resonance space;
Of the input electrode or output electrode, at least one or both, the dielectric filter, wherein Kopu les over Na line, strip line, in that it is formed by a coaxial line, or non-radioactive line. Wherein and resonance space is plural number, enter the high-frequency signal the input electrode to one of said resonant space, the output electrode is taken out of the high-frequency signal from the other of said resonant space, the input electrode and the output The dielectric filter according to claim 4 , wherein the electrode is formed of a coaxial line .   In the waveguide formed between the lower conductor and the end surface of the support member across the dielectric substrate, the dielectric substrate has a thickness and relative dielectric constant that attenuates propagation of a high-frequency signal having a resonance frequency. 6. The dielectric filter according to claim 4, wherein the dielectric filter has a rate. A lower conductor and an upper conductor; a first dielectric substrate disposed in contact with the lower conductor; and a second dielectric substrate disposed in contact with the upper conductor;
The first dielectric substrate and the second dielectric substrate are opposed to each other via a support member, and a resonance space is formed therebetween,
An input electrode for inputting a high-frequency signal to the resonance space; and an output electrode for extracting a high-frequency signal from the resonance space;
Of the input electrode or output electrode, at least one or both, the dielectric filter, wherein Kopu les over Na line, strip line, in that it is formed by a coaxial line, or non-radioactive line.   8. The dielectric filter according to claim 7, wherein the support member is a cylindrical conductor, and open ends on both sides of the cylindrical conductor are in contact with the first and second dielectric substrates.   The dielectric filter according to claim 8, wherein the cylindrical conductor is a cylindrical conductor.   Waveguides respectively formed between the lower conductor and the end face of the support member across the first dielectric substrate, and the upper conductor and the support member across the second dielectric substrate 8. The waveguide formed between the first and second dielectric substrates, wherein the first and second dielectric substrates have a thickness and a relative dielectric constant so as to attenuate the propagation of a high-frequency signal having a resonance frequency. The dielectric filter according to claim 9.   A wireless communication device equipped with the dielectric filter according to any one of claims 4 to 10.

Images